Use of Sewage Treatment Plant (STP) Sludge for Fertilization of Rubber Trees (Hevea Brasiliensis)

Objectives: To evaluate the effect of sanitized sewage sludge from Wastewater Treatment Plants (WWTP) on the growth of rubber tree (Hevea brasiliensis), comparing it with conventional organic and chemical fertilization. Theoretical Framework: The disposal of WWTP sludge poses technical, economic, and environmental challenges. Its agricultural use emerges as a sustainable alternative, providing essential nutrients for plants, reducing the amount of waste sent to landfills, and aligning with circular economy principles. Method: The experiment was conducted in a randomized block design with nine treatments and two replications, spaced 6 × 3 m, three years after planting. Increasing doses of nitrogen from sanitized sludge were applied, as well as bovine manure, urea, and a control without fertilization. Growth variables measured were total plant height and diameter at breast height (DBH). Results and Discussion: Higher nitrogen doses from sludge promoted greater growth, especially in DBH, a variable related to latex production. The 70 g N/plant dose showed performance comparable to conventional fertilization, while higher doses enhanced vegetative development. These findings confirm the feasibility of sludge as an agricultural input and reinforce its contribution to soil fertility. Research Implications: The study demonstrates that sanitized sludge can replace or complement traditional fertilizers in rubber tree cultivation, reducing costs and environmental impacts, while offering a sustainable solution for WWTP sludge management. Originality/Value: This research expands knowledge on the agricultural use of sludge in perennial crops of economic interest, such as rubber tree, which are still little explored in the literature, highlighting its potential to strengthen sustainable agricultural practices.